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https://github.com/saymrwulf/curve25519-dalek-source.git
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Add Edwards doubling implementation.
This commit is contained in:
Henry de Valence
parent
c4617b28a9
commit
8e38ff2859
2 changed files with 100 additions and 8 deletions
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@ -51,7 +51,50 @@ impl From<ExtendedPoint> for CachedPoint {
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CachedPoint(F51x4Reduced::from(x))
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}
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}
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impl ExtendedPoint {
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pub fn double(&self) -> ExtendedPoint {
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// Set tmp0 = (X1 Y1 X1 Y1)
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let mut tmp0 = self.0.shuffle(Shuffle::ABAB);
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// Set tmp1 = (Y1 X1 Y1 X1)
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let mut tmp1 = tmp0.shuffle(Shuffle::BADC);
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// Set tmp0 = (X1 Y1 Z1 X1+Y1)
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tmp0 = self.0.blend(&(tmp0 + tmp1), Lanes::D);
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tmp1 = F51x4Reduced::from(tmp0).square();
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// Now tmp1 = (S1 S2 S3 S4)
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// We want to compute
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//
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// + | S1 | S1 | S1 | S1 |
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// + | S2 | | | S2 |
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// + | | | S3 | |
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// + | | | S3 | |
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// + | |16p |16p |16p |
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// - | | S2 | S2 | |
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// - | | | | S4 |
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// =======================
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// S5 S6 S8 S9
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let zero = F51x4Unreduced::zero();
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let S1_S1_S1_S1 = tmp1.shuffle(Shuffle::AAAA);
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let S2_S2_S2_S2 = tmp1.shuffle(Shuffle::BBBB);
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let S2_S2_S2_S4 = S2_S2_S2_S2.blend(&tmp1, Lanes::D).negate_lazy();
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tmp0 = S1_S1_S1_S1 + zero.blend(&(tmp1 + tmp1), Lanes::C);
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tmp0 = tmp0 + zero.blend(&S2_S2_S2_S2, Lanes::AD);
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tmp0 = tmp0 + zero.blend(&S2_S2_S2_S4, Lanes::BCD);
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let tmp2 = F51x4Reduced::from(tmp0);
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ExtendedPoint(&tmp2.shuffle(Shuffle::DBBD) * &tmp2.shuffle(Shuffle::CACA))
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}
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}
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impl<'a, 'b> Add<&'b CachedPoint> for &'a ExtendedPoint {
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type Output = ExtendedPoint;
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@ -134,4 +177,35 @@ mod test {
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let Q = &constants::ED25519_BASEPOINT_TABLE * &Scalar::from(8475983829u64);
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addition_test_helper(P, Q);
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}
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fn doubling_test_helper(P: edwards::EdwardsPoint) {
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//let R1: edwards::EdwardsPoint = serial_double(P.into()).into();
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let R2: edwards::EdwardsPoint = ExtendedPoint::from(P).double().into();
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println!("Testing point doubling:");
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println!("P = {:?}", P);
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//println!("(serial) R1 = {:?}", R1);
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println!("(vector) R2 = {:?}", R2);
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println!("P + P = {:?}", &P + &P);
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//assert_eq!(R1.compress(), (&P + &P).compress());
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assert_eq!(R2.compress(), (&P + &P).compress());
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println!("OK!\n");
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}
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#[test]
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fn vector_doubling_vs_serial_doubling_vs_edwards_extendedpoint() {
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use constants;
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use scalar::Scalar;
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println!("Testing [2]id");
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let P = edwards::EdwardsPoint::identity();
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doubling_test_helper(P);
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println!("Testing [2]B");
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let P = constants::ED25519_BASEPOINT_POINT;
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doubling_test_helper(P);
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println!("Testing [2]([k]B)");
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let P = &constants::ED25519_BASEPOINT_TABLE * &Scalar::from(8475983829u64);
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doubling_test_helper(P);
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}
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}
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@ -28,20 +28,17 @@ pub struct F51x4Unreduced(pub(crate) [u64x4; 5]);
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#[derive(Copy, Clone, Debug)]
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pub struct F51x4Reduced(pub(crate) [u64x4; 5]);
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#[derive(Copy, Clone)]
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pub enum Lanes {
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D,
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AB,
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AC,
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}
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#[derive(Copy, Clone)]
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pub enum Shuffle {
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AAAA,
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BBBB,
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BADC,
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ADDA,
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CBCB,
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ABDC,
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ABAB,
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DBBD,
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CACA,
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}
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#[inline(always)]
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@ -51,14 +48,28 @@ fn shuffle_lanes(x: u64x4, control: Shuffle) -> u64x4 {
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match control {
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Shuffle::AAAA => perm(x.into_bits(), 0b00_00_00_00).into_bits(),
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Shuffle::BBBB => perm(x.into_bits(), 0b01_01_01_01).into_bits(),
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Shuffle::BADC => perm(x.into_bits(), 0b10_11_00_01).into_bits(),
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Shuffle::ADDA => perm(x.into_bits(), 0b00_11_11_00).into_bits(),
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Shuffle::CBCB => perm(x.into_bits(), 0b01_10_01_10).into_bits(),
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Shuffle::ABDC => perm(x.into_bits(), 0b10_11_01_00).into_bits(),
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Shuffle::ABAB => perm(x.into_bits(), 0b01_00_01_00).into_bits(),
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Shuffle::DBBD => perm(x.into_bits(), 0b11_01_01_11).into_bits(),
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Shuffle::CACA => perm(x.into_bits(), 0b00_10_00_10).into_bits(),
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}
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}
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}
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#[derive(Copy, Clone)]
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pub enum Lanes {
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D,
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C,
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AB,
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AC,
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AD,
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BCD,
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}
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#[inline]
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fn blend_lanes(x: u64x4, y: u64x4, control: Lanes) -> u64x4 {
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unsafe {
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@ -66,13 +77,20 @@ fn blend_lanes(x: u64x4, y: u64x4, control: Lanes) -> u64x4 {
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match control {
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Lanes::D => blend(x.into_bits(), y.into_bits(), 0b11_00_00_00).into_bits(),
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Lanes::C => blend(x.into_bits(), y.into_bits(), 0b00_11_00_00).into_bits(),
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Lanes::AB => blend(x.into_bits(), y.into_bits(), 0b00_00_11_11).into_bits(),
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Lanes::AC => blend(x.into_bits(), y.into_bits(), 0b00_11_00_11).into_bits(),
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Lanes::AD => blend(x.into_bits(), y.into_bits(), 0b11_00_00_11).into_bits(),
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Lanes::BCD => blend(x.into_bits(), y.into_bits(), 0b11_11_11_00).into_bits(),
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}
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}
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}
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impl F51x4Unreduced {
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pub fn zero() -> F51x4Unreduced {
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F51x4Unreduced([u64x4::splat(0); 5])
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}
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pub fn new(
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x0: &FieldElement51,
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x1: &FieldElement51,
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